you can use a weird xbox 360 controller straight out of the box on the PC as it is USB, to use the wireless pads however you will neeed the xbox 360 crossfire adapter.
This simply plugs in to a usb port on your pc and will allow you to use a wireless xbox 360 controller on your PC (or any wireless 360 peripheral for that matter inc steering wheel). I know this as i have just bought one myself HERE is a link to what you need.

im using THIS monitor at the moment and find it great. Thing is it only has 1 analog input which became a problem when i wanted to put my xbox 360 in it aswell as i had to keep swaping leads between my pc and 360...a KVM switch sorted that tho.

Maybe the psu cant handle the load. I know in your sig it says 500W but if its not a qaulity branded one that 500W stated is more than likely the max output it can handle, and even then the output wouldnt be to stable. Try unplugging all things not essential, case fans etc